1. Field of the Invention
This invention relates to braze fixtures, and especially to fixtures used in the brazing of plate type heat exchangers in which multiple plate and corrugated fin elements, and appropriate spacers, are stacked one upon another, held so that the parts maintain an assembled relation, and brazed to form a unitary heat exchange core or device. In this operation, fixtures play a part both in defining a configuration to receive and position stacked parts and in holding the parts assembled during brazing.
2. Description of the Prior Art
Braze fixtures of the prior art are known which include locators to define a configuration of square-like or other shape corresponding to the peripheral outline of the heat exchangers. Upon an assembled heat exchanger being brazed, however, it has been necessary to effect prior removal of the locators in order to accommodate expansion of the parts as they are heated in the brazing process. Removal of the locators, however, leaves the assembled heat exchanger vulnerable to distortion and to collapse or protrusion of individual components. This is a particular hazard in working with very thin materials and with relatively elongated parts not inherently resistant to distorting pressures. Workers in the art attempt by precise assembly and by carefully controlled techniques to reduce distortion to a tolerable level. Still, rectangular or square heat exchangers which come out of the brazing process out of square or otherwise distorted are not uncommon in heat exchange fabrication. Attempts to cope with this problem using clamps have had limited success since the clamps, if made tight, restrain normal expansion of the parts, and, if made loose, fail in their intended purpose.
My prior application Ser. No. 829,881, filed Sept. 1, 1977, is addressed to a solution of the present problem and discloses an effective braze fixture. The fixture of the instant invention is an improvement over that of my prior application in that it adapts more readily to embodiments requiring a high degree of compactness. Also, in the instant fixture, movement of parts locators is more readily controlled and parallelism more positively assured. In this connection, it will be understood to be increasingly difficult to maintain a close, uniform contact with a corner of a heat exchanger core, as the height thereof increases.